Do I have a pre-aggressive dog?

You may have a confident pup, but he sounds 100% normal LOL.  But, I can guarantee that if you "snap his leash up into his mouth" for very long, you may create an aggressive dog.  Stop that right now - try painting the leash with a little Vicks Vapo Rub to make it uninteresting as a chew toy.  When he wants to take the leash, substitute an appropriate toy and praise him for taking it.  This is a retriever, and they can be very mouthy as youngsters.  The key is to learn how to deal with it in a benevolent way, but a way that does not allow him to practice any behavior that you don't want him to do as an adult.  If he goes at your pant leg, you need to withdraw - I usually just squeeze into the bathroom and leave the pup outside for a couple of minutes.  The object is to teach him that if he bites pant legs, his playmate disappears.  You can "yelp" to help make your point.  Prevention is a better way to handle this - lots and lots of exercise - it's very hard to nip anyone if your tongue is lolling out on the floor.  Get him in to a positive training class where he gets lots of play time with other puppies.
[linkhttp://www.apdt.com]www.apdt.com[/link] and [linkhttp://www.clickertraining,com]www.clickertraining,com[/link] both have trainer searches.  It sounds like you are a novice owner, so you probably should take more than one class.  Also, great book:
"Parenting Your Dog"  - you can find it on dogwise.com.  If you have kids, please also get "Raising Puppies and Kids Together".

I agree with Spirit.  Get that pup into puppy class and then go for obedience training.  Keep us posted.

he sounds perfectly normal in every way. Some folks actually encourage their dogs to grab and play tug with the leash (on command of course) so they always have a reward available for their dog.
How much exercise and play and socialization with other dogs does he get? if he's pestering you 24 hours a day it's probably not enough.  He needs lots of play dates with other dogs at this age, and tons of playtime with you. The great thing about puppies is you can easily combine play with training and exercise-- ask for a sit, throw the ball. Get two people and pratice your recall by playing "puppy bounce". Things like that.

Oh my, where to start?
If you ever have hopes of having him crate trained DO NOT put him in there as punishment. If you havnt enrolled him in obediance classes where exactly do you expect him to know what you want from him? He has NO idea and "using your growling vioce' only tells him he is displeasing you, its not teaching him anything. It seems to me that you wernt aware of puppy behavior prior to getting a puppy. He NEEDS attention, he went from having a whole litter of playmates to just you, you have to understand YOU are his life now. He NEEDS exersice, obediance classes, socialization. When I first got Rory someone sent me this, it really made me question what kind of dog owner I wanted to be, remember you get what you put into the dog...............
 
Please Master, I am so tired of hurting. Did you know that I only wanted you to love me and give me lot's of praise and affection? Why did you choose to yell and scream at me when I misbehaved? At times, you resorted to physical abuse. Remember, you were the one who chose to take me home. After you separated me from my mother and siblings, why did you change your mind? Wasn't I the same soft, lovable cuddly puppy? Was I wrong in expecting you to be my new family?

When I pottied in your domain, it wasn't that I was stupid, like you yelled. After all, going potty at any time or place was very natural for me. Did you really think I was just trying to displease you? I just didn't understand what you expected from me. Can you imagine how totally crushed and humiliated I felt when you shoved my face in the mess I made, then threw me outside?

How about the time you kicked me across the room, calling me a dumb, stupid mutt. I, like you, have sensitive feelings and strong emotions. How was I to know that your new boots were not toys? It was so boring, being at home all alone, with nothing to do. I only wanted something to play with and chew on. did you know that my poor body ached for days afterwards? Yet, you wondered why I cringed and whimpered at your touch.

Those cold winter nights that I stood, shivering, wiht my nose pressed against the glass, softly whimpering to come in, you just ignored me. I learned a long time ago not to bark. I still can feel you swatting me on the head, as you yelled for me to shut up. There you sat, all warm and cozy, by the fire, sipping wine and reading your favorite book. Oh, how I yearned for your companionship! Just to lay at your side, or perhaps curl up at your feet; to have you reach down and touch me every once in awhile. Couldn't you understand I needed your love and affection, just as I wanted to give you mine? Maybe you just didn't care.

Remember how you complained about my shedding, getting hair everywhere, telling me I was nothing but a stinking, grubby dog? Don't you think I would have appreciated being brushed, vaccumed and bathed? My appearance is important to my feelings of self worth, just as yours are.

Not once did you ever take me to have fun. All the times you went hiking in the mountains, I was left at home. Didn't you ever think how much I would enjoy running and exploring new things? I would have been happy if you would have just played ball with me. But no, you didn't have time for me. I felt like I was a millstone around your neck.

How would you like to spend your life alone, with no social contacts, eating and drinking out of dirty dishes? Can't you smell my bed? It should have been washed months ago.

Now look at me! Only 18 months old and condemned to die. They say I'm unpredictable, that I could be dangerous, and possibly vicious. This is not true! I'm not mean like they say. It's just that I'm so scared of being hurt again, that I react without thinking. Later, I am sorry for my actions and regret that I am no longer capable of controlling myself.

If only someone would try to understand me and help me to overcome my fears! I just need someone I can feel safe with, whom I can trust. Someone who will have confidence in me. I haven't changed inside. I'm still the same, fun loving, affectionate puppy I used to be. I need help to express these feelings once again

Thank you for your responses.  I am not a novice dog owner.  I have helped raise other puppies with my parents, but have not had any that are as active and dominent as my little guy.  He is my first dog on my own, but not the first dog I have lived with. 
 
I am signed up for puppy classes that start in two weeks.  It is the same school I went to to train my family's dog.  Hopefully things will go better after we start there.
 
Sue

You didnt mention what kind of dog it is? That makes a HUGE differnece also. My pit bull has defintly taught me the difference of disobediance and plain old stuborness, ha ha!

Buddy is a boston terrier/corgi mix. 

I hear Corgi's are pretty wel mannered but can have a funny mischevious streak to them. As for the Boston Terriers, they are........Boston Terrors, and that is meant in a good way. To know them is to love them, they are mischevious lil rascals with a mind of their own that NEED leadership. If he dosnt have you as a leader he will do what ever the heck he wants and go to town! Oh man my aunt used to have one, he was so funny, he'd hold a grudge and I SWEAR he plotted against her if she missed a morning walk. He would do stufff like go scatter all the pillows off her bed, take her dirty clothes outta the hamper and drag them all through the house, just goofy stuff. This kinda sound sliek you guy, basically EVERYTHING is a game to him. When he jumps on you and you swat at him or something he is like "woo hoo, I got her attention"! I can tell you he is going to be a fun dog that will make you laugh BUT he NEEDS discipline. Oh amn I can just picture the lil goo fnow, can we get some pics?

Sue--

Twelve weeks is still awfully young, and much of what you are describing sounds like a typical active puppy, not a precursor to a problem. Probably one of the biggest things you should concentrate on is getting your active pup a lot of exercise. This will solve many of the problems you're describing without having to have a power struggle. And if you can incorporate some lessons into your play and exercise, you will be subtely establishing your role as leader from the get go, without having to make it a battle.

For inappropriate chewing, a quick substitution of a more appropriate chewing substance (toy or bone) usually will help the dog to learn to differentiate between what is okay to chew and what's not. I wouldn't worry about the leash chewing unless it's making walking him difficult for you -- the bite the leash game is a common puppy behavior, and not necessarily indicative of a bigger problem. Often, it's perceived as a fun game. My lab mix, Tiffany, played this game with me for nearly 15 years, and she didn't have a dominant bone in her body.

The growling in play that you mentioned doesn't sound like aggression, just like active play and some vocalizing. If your pup is growling when you remove him from the couch or try to take his food bowl, you've got a problem. If he's growling during tug of war, he may just be playing with you.

Remember, too, that different dogs make different sounds, and all don't necessarily fall into the category you might first thing. For instance, Jessie has a weird noise she makes that we've dubbed her "pet me" noise. It may sound like a growl to an outsider, but it's not. It's merely her way of "talking," or requesting more attention. If I don't feel like petting her,
I'll say, "No, Jess, no more petting," and she'll stop (well, first she'll roll on her back and shoot for a belly rub, but if I ignore that, then she'll eventually give up and go bother her cats!).

If I'm talking to her in the a.m. and I stop talking to brush my teeth, she'll make this weird gargling noise which basically means she'd like me to continue talking to her. It's not remotely aggressive, though it could be confused for a growl by someone who didn't know her. I've heard her growl at intruders in her Cujo voice, and it's a whole different noise. But the first few times she made the gargling pet me/talk to me noise, I was worried I had a problem. But I soon learned that she was just talking to me, these are private noises she only makes with her family, and I certainly didn't want to punish her for that. Playful noises or talking noises may well sound like growling and not be at all. Your dog may like to vocalize, and this doesn't have to mean aggression or dominance. And puppies tend to be more vocal than older dogs. They have a lot of energy and a lot to say! : )

The mouthing or nipping at your legs for attention is also normal trying to get your attention behavior (in the absence of hands), though that's one you'll want to break your pup of for obvious reasons. I used "no bite" as the command for this, and then quickly subtituted something else in her mouth to distract her -- a toy or a bone, and then praised her when she chewed on it.

Out here, most of the serious trainers won't even take a dog for training before five months, because they believe puppies much younger than that aren't mature enough for serious training, though many offer puppy socialization classes to start the process. This will help your dog get exercise and begin learning manners, and help you to see what is and is not normal and appropriate puppy behavior.

Additionally, this is a great time in your pup's life to start the socialization process, so the more places you can take your dog, the better. Regular time with you and exposure to new places and experiences will help ensure a happy, healthy and well adjusted dog. This is also good pre-training if you later decide you'd like to get your dog TDI certified. And it has the added benefit of tiring your dog out mentally and physically, which will help your dog to be less hyper in the home.

You want to work on exercise, basic commands, crate training, quiet command (easier when the dog is tired), stopping the mouthing behavior (which may take a while, and is totally normal), all that stuff, but I wouldn't worry too much. Nothing in your post sounds like aggression or the beginning of a "problem dog." Just an active, lively pup who wants as much of your attention as possible.

Look into obedience and socialization classes, but try not to worry. Buddy sounds like he's doinig just fine!

Jan